Question for the creator and users of this automation logic.When is a section free?

I am trying to walk through the logic and my first thought was that with 3 trains, only one section would be free at a time, allowing only one train to move at a time. This is clearly not the case in the videos.Is a section considered free until a train crosses the slowdown sensor?And then considered free again as soon as the acceleration starts?

I am considering trying to set up a similar set up with an arduino and motor shield that has 4 pwm outputs. But truthfully, I only just ordered the starter set and some scenery. I have to confirm that I can work with this more challenging scale before I get more track. (but the ir sensors are ordered and I have several arduinos already)

Watching the automation in action is a little mesmerising but once you watch it for a while, it's fairly easy to predict when a particular train is about to start...which amuses the watching public as you wave the train off...and off it goes!

I'll try and describe how the sequencing works. Sections 1 and 3 are the runaround loops...and a train takes approx. 10 seconds to run off the end of section 4 (or 2), round the loop, and to slow and stop at the end of section 1 (or 3). A train running from the station at one end of the bridge (the end of section 1 [or 3]) takes around 25 seconds.

Lets start with trains stopped at the ends of sections 1, 3 and 4.- Section 2 is free, so the train at the end of section 1 starts off (over the bridge). It has 25 seconds to reach the end of the section.- As soon as the above train leaves the station, it has cleared section 1...which is now free.- The train at the end of section 4 now starts...... and runs to the end of section 1- As soon as this train leaves the station, it has cleared section 4...which is now free.- The train at the end of section 3 now starts...... and runs to the end of section 4.

We now have three trains running....the leading train is now about half way over the bridge, the second train is slowing to stop at the end of section1, and the third train is a few seconds into crossing the bridge....and in say 5 seconds it will pass the leading train coming the other way. Continuing the sequence...- The second train stops at the end of section 1. It can't progress because there's a train in section 2.- The leading train reaches the end of section 2. Section 3 is clear, so it doesn't stop and continues into section 3.- As soon as this train passes through the station, it has cleared section 2...which is now free.- The train in section 3 now reaches the end of the section,,,,and stops because section 1 is occupied.- As section 2 is now clear, the train at the end of section 1 now starts off into section 2....section 1 is now free.

I hope by now you will appreciate how the sequencing works. The order of sections becoming free is nominally 4,3,2,1.

One strange little quirk I've noticed is that on occasions, a train might creep very slowly when it should be stationery...and it SPADs and once in the next section, runs off following the train already in the section. This usually happens on the long sections. All is not lost, as the sequencing stops it at the end of the section, giving time for the sequencing to step back into "time". Weird!! But fun to watch....and if any visitors notice, I simply say the driver's in trouble!!